EP3585935A1

EP3585935A1 - Hybrid turf or artificial turf with inhomogeneous latex backing

Info

Publication number: EP3585935A1
Application number: EP17723118.0A
Authority: EP
Inventors: Stephan Sick; Ivo LOHR; Mark HEINLEIN; Hamish Sutherland
Original assignee: Polytex Sportbelage Produktions GmbH; Stadia Turf Technology Pte Ltd; Technology Licensing Corp
Current assignee: Polytex Sportbelage Produktions GmbH; Stadia Turf Technology Pte Ltd; Technology Licensing Corp
Priority date: 2017-03-23
Filing date: 2017-05-12
Publication date: 2020-01-01
Also published as: WO2018171910A1

Abstract

The invention relates to an artificial turf (140) comprising: - a layer (132) of artificial turf fibers (130), the layer having an upper side (US) and a lower side (LS), wherein first portions of the artificial turf fibers protrude from the upper side and second portions of the artificial turf fibers protruding from the lower side, the first portions forming artificial grass blades (130); - a backing on the lower side of the layer, the backing being a solidified, inhomogeneous latex mixture of a first latex (602, 706) and a second latex (604, 708), the first latex in the dry state being less water-swellable than the second latex in the dry state, the backing contacting at least the second portions and mechanically fixing the artificial turf fibers in the layer.

Description

HYBRID TURF OR ARTIFICIAL TURF WITH INHOMOGENEOUS LATEX

BACKING

Description

Field of the invention

This invention relates to hybrid turf supports and artificial turf and how they are manufactured.

Background and related art

Hybrid turf and artificial turf are commonly used for sports fields and have a grasslike look and feel but require less water, are more resistant to wear and tear, and have other advantageous properties over typical natural grass surfaces. Hybrid turf is a combination of natural grass and artificial grass, where the artificial grass accounts for 3-5% of the playing surface. By adding artificial grass to the natural grass, the playing surface becomes more durable and consistent. With hybrid turf the artificial grass fibres are attached to a backing via weaving or tufting to create a hybrid turf support with horizontal and vertical components.

The hybrid turf support will overlay a soil profile and will be infilled with sand-soil growing medium prior to seeding or sprigging. Typically the fibre length is 60mm and the growing medium infill depth is 40mm. The 20 mm of fibre remaining above the infill protects the natural grass and in doing so creates the extra durability and consistency expected of hybrid turf. These parameters of laying and infilling are not dissimilar to how infilled artificial turf is installed and many of the hybrid turf offerings have been developed by artificial turf companies.

The hybrid turf support, consisting of a backing and upright fibres, adds versatility. Hybrid turf can be supplied in a turf roil that is prepared and grown off-site and then installed on-site as a 'lay and play' solution. With this option the fibres and backing of the hybrid turf support provide the turf roll with the necessary vertical and horizontal stability to guarantee immediate play. Traditionally 'thick-cut' soil-based turf rolls have been used for this purpose. However, without the support provided by the hybrid turf support, they inherently lack consistency which adversely impacts performance. The hybrid turf support's backing adds challenges from an agronomic point of view, as it may impede drainage, aeration and root development, unless the backing is very open. Backings that are open, however, cannot mechanically anchor or hold the vertical artificial grass fibers in the backing during the tufting process. This holding or anchoring is referred to as tuft bind. If the fibers are not anchored into the backing they can be pulled out of the backing during the process of placing the growing medium in the support, thereby destroying the integrity of the hybrid system.

This problem has been overcome by adding a second biodegradable component in the backing which provides mechanical hold but then degrades to create voids for drainage, aeration and root development, as described in US patent US006035577, and others. This works adequately when tufting with fibrtllated tape fibers but does not work well for fiber bundles made from monofilaments. These monofilament fibre bundles are far easier to dislodge from the backing during the placing of growing medium. To anchor monofilaments bundles yet another step is required, that being the application of a secondary backing which adheres the fibers to the backing and thereby increases tuft bind. A similar step is done in the manufacturing of artificial turf systems.

This method is unacceptable for hybrid turf systems, however, because a secondary backing would seal off the lower side of the support. The effect would be to limit root growth, drainage and aeration, and thereby reduce the strength and performance of the natural grass.

Currently, hybrid turf supports vary greatly in their construction and application. Some hybrid turf products have similar fibre weight and backing weight to synthetic turf, hence they are ideal for a community training pitch. Other hybrid turf products are designed for temporary installation, for example the hybrid turf is installed over synthetic turf for one football match. At the completion of the match the hybrid turf may be disposed of or recovered and made ready for the next use. If disposed of, it is important the materials are separated (grass, sand and plastic) and recycled.

Summary It is an objective of the present invention to provide an improved artificial turf or a hybrid turf support for hybrid turf and a corresponding method for the production thereof as specified in the independent claims. Embodiments of the invention are given in the dependent claims. Embodiments of the present invention can be freely combined with each other if they are not mutually exclusive. In a first aspect, the invention relates to an improved hybrid turf support for use with natural grass to form a stable hybrid turf system, the hybrid turf support comprising:

(a) a carrier having an upper side and a lower side;

(b) a plurality of artificial turf fibers engaging with the carrier, first portions of the artificial turf fibers protrude from the upper side of the carrier, and second portions of the artificial turf fibers protrude from the lower side of the carrier; the first portions of the artificial turf fibers form artificial grass blades; and (c) a backing on the lower side of the carrier, the backing comprising a solidified inhomogeneous liquid mixture of a first latex and a second latex; wherein the first latex in the dry state is less water-swellabie than the second latex in the dry state; wherein, in use, the different swelling properties of the first and second latex result in water-induced disintegration of the backing.

The plurality of artificial turf fibers may engage with the carrier in any manner devised by the person skilled in the art. For example, the plurality of artificial turf fibers may be tufted, woven or knitted into the carrier. Where the plurality of artificial turf fibers are loosely affixed to the carrier, for example by tufting, then the backing securely affixes the plurality of artificial turf fibers to the carrier.

Where the plurality of artificial turf fibers are already securely affixed, for example, by knitting as in international patent application no PCT/IB2016/001367, then the backing provides other benefits. In particular, a hybrid turf support needs to have a carrier which enables water to drain and penetration of the growing roots of the natural grass plants. In use, the different swelling properties of the first and second latex result in water-induced disintegration of the backing of the present invention. This disintegration may be water-induced microscopic cracks which are expanded by the roots of the natural grass plants or the backing may disintegrate into small pieces. However, prior to the first exposure to water, the backing aids in retaining growth media for the natural grass in place while infilling. Further, the latex used in the backing may be chosen to ensure that the backing remains intact for a sufficient period of time to provide support during transport and installation of a hybrid turf system to guarantee the integrity of each turf roll. However, healthy natural grass plants are desired for a longer time period, then the backing will need to disintegrate further after installation.

The carrier may comprise any reinforcing root-permeable mat prepared in any manner devised by the person skilled in the art depending on the desired

characteristics for the final hybrid turf system. For example, the carrier may be woven, non-woven or knitted. Any material commonly used in the art for making a hybrid turf support may be used to make the carrier used in the hybrid turf support according to the invention. For example, the carrier may be made from materials selected from the group consisting of biodegradable materials and/or nonbiodegradable materials, and these materials may be of a biological (natural) or non-biological (synthetic) origin and/or composition. The material may be chosen depending on the desired characteristics for the final hybrid turf system. The yarns may also be treated to provide beneficial properties, for example, impregnated with insect repellent or coated to provide resilience.

Any material commonly used in the art for making artificial turf fibers may be used. The grass-like fibers may be monofilaments, multifilaments, fibriliated, tape or texturized. For example, the grass-like fibers may be selected from the group consisting of biodegradable synthetic artificial turf fibers, non-biodegradable synthetic artificial turf fibers, biodegradable non-synthetic artificial turf fibers, nonbiodegradable non-synthetic artificial turf fibers and mixtures thereof. The artificial turf fibers may be chosen depending on the desired characteristics for the final hybrid turf system, for example, softness, resilience, or water retention. The artificial turf fibers may also be treated to provide beneficial properties, for example, impregnated with insect repellent or coated to provide resilience.

The key to a strong and healthy natural grass turf plant is a strong root system. Young roots are vigorous and responsive, for example they readily absorb nutrients and water, whereas, old, mature roots, are less responsive and less efficient. If the hybrid turf system is installed (planted) on an impermeable root membrane, for example plastic at the nursery, and the roots have "balled" on the underside of the hybrid turf system over time, it is important that these old roots (dead organic material) are removed at the time of harvest or subsequent installation. The removal of these old roots will lessen congestion in the growth media and will allow more oxygen to enter the growth media to benefit the new roots (and allow carbon dioxide to exit the growth media). The removal of old roots improves drainage from the turf surface through the growth media which will also benefit the new roots. The removal of old roots also stimulates the creation of new roots, via the process known as "root-pruning". All are essential for the establishment of a new, strong root system and the creation of natural grass turf plants which are healthier, stronger and durable. Hence the health of the root system of the natural grass turf in the hybrid turf system can be improved via using a removable root-pruning backing as taught in international patent application no WO 2012/159145. In a second aspect, the invention relates to a method of producing a support for hybrid turf. The method comprises:

- incorporating artificial turf fibers into a carrier— the carrier has an upper side and a lower side; the first portions of the incorporated artificial turf fibers protrude from the upper side, and the second portions of the artificial turf fibers protrude from the lower side; the first portions form artificial grass blades;

- generating an inhomogeneous liquid mixture of a first latex and a second latex; the first latex in the dry state is less water-swellable than the second latex in the dry state;

- after having incorporated the artificial turf fibers, applying the inhomogeneous liquid mixture on the lower side of the carrier such that the inhomogeneous liquid latex mixture wets at least the second portions; and

- solidifying the inhomogeneous liquid latex mixture to form a solid backing of the support; the backing mechanically fixes the artificial turf fibers in the carrier; the carrier with the backing and the incorporated artificial turf fibers form the support.

Using a mixture of two different types of latex having different swelling capabilities for generating the backing of support in hybrid turf may have the advantage that the different swelling properties will result in mechanical shear forces at the contact areas of the first and second latex when the backing contacts water. Typically, the backing contacts water when natural grass seeds or sprigs are added onto the support at a sod farm and when the support is irrigated in order to grow natural grass plants on the support. The mechanical shear forces may be so high that the backing disintegrates into small pieces after a few or even after the first irrigation operation. If the difference in the swelling properties of the first and second latex is too low to result in a complete disintegration of the backing, at least microscopic cracks in the backing material are created that allow water to penetrate the backing and ease the penetration of the backing by the growing roots of the grass plants. The effect of the water-induced microscopic cracks or the water- induced disintegration of the backing is that the newly rooting grass plants can move easily through these openings, which also allow for downward water movement and gas exchange. The penetration of the roots through the cracks will cause further disintegration. It has been observed that, in some prior art hybrid turf systems, the roots of the grass plants clog all openings of the carrier material of the support which will then impede drainage, aeration and root development. When this occurs, moisture retention in the soil becomes too high and air porosity in the soil is correspondingly reduced. The soil becomes anaerobic which is detrimental to root growth and plant health. The natural grass will become weak and susceptible to disease, will not be durable and will not recover from wear and tear caused by use. Hence the natural turf will deteriorate and then die.

By using a backing that consists of an inhomogeneous mixture of two types of latex having different swelling capabilities, said disadvantages may be avoided. As the backing disintegrates when put in contact with water, space is created to allow for root growth through the backing, drainage of water and exchange of gases. This results in a favorable growing environment and strong, healthy grass plants which are able to recover more quickly from wear and are less susceptible to disease. The overall effect is a more durable and consistent natural grass surface.

Embodiments of the invention may have the advantage that the heterogeneous latex backing provides sufficient tuft bind to keep the fibers in the backing during the infilling process. Once complete, the fibers are held within the hybrid turf support by the mechanical forces of the backing, a synthetic mesh, infill and grass roots. The use of a heterogeneous latex mixture with different swelling capabilities allows to destroy or destabilize the backing once it is no longer needed.

Thus, embodiments of the invention may allow for providing a support for hybrid turf that ensures that natural grass plants do not die as a result of waterlogging.

In another beneficial aspect, the application of a latex backing increases the dimensional stability of the hybrid turf support. Stability is essential during transportation to the sod farm or the use site, and establishment of the grass within the support. The process of establishment includes sewing the rolls together and infilling the rolls with growing medium. The infilling process is done by using a topdresser to spread thin layers of the growing medium and then sequentially raking and brooming the infill layers into the fibres. Thus, a strong support is provided that firmly keeps the artificial fibers in place and vertically oriented and accommodates the process of establishing the grass. In a further aspect, the invention relates to a method of producing artificial turf. This method comprises:

- generating a layer of artificial turf fibers; the layer has an upper side and a lower side; the first portions of the artificial turf fibers protrude from the upper side, and the second portions of the artificial turf fibers protrude from the lower side; the first portions form artificial grass blades;

- applying the inhomogeneous liquid mixture on the lower side of the layer such that the inhomogeneous liquid latex mixture wets at least the second portions; and

- solidifying the inhomogeneous liquid latex mixture to form a solid backing for the artificial turf; the backing mechanically fixes the artificial turf fibers in the layer; the backing and the layer of artificial turf fibers form the artificial turf.

In analogy to the method for producing a hybrid turf support, using a mixture of two different types of latex having different swelling capabilities for generating artificial turf may have the advantage that the different swelling properties wi!! result in mechanical shear forces at the contact areas of the first and second latex when the backing contacts water.

Typically, the backing contacts water when the artificial grass is installed at the use site and is exposed to rain. The mechanical shear forces resulting from the swelling of the first and second latex may be so high that the backing disintegrates into small pieces after just the first rainfall. If the difference in the swelling properties of the first and second latex is too low to result in a complete disintegration of the backing, at least microscopic cracks in the backing material are created that allow water to penetrate the backing and improve drainage It has been observed that, in some prior art artificial turf systems, after several months or years of use, debris of all kinds may clog the openings of the artificial turf. As a result, water could not leave the artificial turf, and puddles of unabsorbed rainwater formed. Sometimes, artificial turf-based sports grounds could not be used after heavy rainfalls for days, until all puddles had evaporated. In a further beneficial aspect, the improved drainage may help cooling the surface of a sports field when air is blown through the synthetic turf system.

By using a backing that consists of an inhomogeneous mixture of two types of latex with different swelling capabilities, said disadvantages may be avoided. As the backing disintegrates when put in contact with water, the drainage through the artificial turf is improved, and water has sufficient space for penetrating the artificial turf and reaching a soil layer even if a significant amount of debris has accumulated on the sports ground over time. Nevertheless, during the transport of the artificial turf from the production site to the use site, the backing stabilizes the artificial turf and the fibers and eases the installation of the turf at the use site.

Thus, embodiments of the invention may allow providing artificial turf that ensures that rain can infiltrate the ground even after debris of all kinds may have

accumulated on the artificial turf over several years of use.

In a further beneficial aspect, the application of a latex backing increases the stability of the artificial turf so it can easily be transported to the use site. The robustness of the artificial turf against transport and transplantation damage may be increased.

Adding a liquid backing that incorporates at least some ("second") portions of the fibers may have the advantage that the artificial turf fibers are more firmly fixed in the support of the hybrid turf or in the artificial turf.

According to embodiments, the first and/or second latex is an emulsion of a copolymer in an aqueous medium. The copolymer is a copolymerization product of a polymerizabie polymer and one or more monomers. The one or more monomers are selected from a group comprising:

- styrene or a substituted styrene; and

- an acrylate and/or methacrylate.

According to embodiments, the polymerizabie polymer is water-swellable.

According to embodiments, the polymerizabie polymer is water-swellable and is a polymerizabie starch or a polymerizabie starch derivative. Using starch may be advantageous, as starch is a biodegradable substance. The backing can be disrupted very quickly by applying water to the hybrid turf or the artificial turf such that the water, e.g., rain or irrigation, contacts the backing. The resulting fragments of the backing can then be degraded at least partially by microorganisms over a longer period of time, typically weeks and months. Thus, the backing may largely or completely be degraded.

According to embodiments, the method further comprises generating the copolymer of the first (less water-swellable) latex by copolymerization of a first

copolymerization mixture. The first copolymerization mixture comprises:

- 20% to 40% by weight of the first copolymerization mixture of the styrene or the substituted styrene;

- 20% to 50% by weight of the first copolymerization mixture of the aery late and/or methacrylate;

- 5% to 20% by weight of the first copolymerization mixture of one or more

ethylenically unsaturated monomers (e.g., acrylate, methacrylate, styrene); and

- 1 % to 15% by weight of the first copolymerization mixture of a not-yet- polymerizable form of the po!ymerizable polymer.

According to embodiments, the method further comprises generating the copolymer of the second (water-swellable) latex by copolymerization of a second

copolymerization mixture comprising:

- 20% to 40% by weight of the second copolymerization mixture of the styrene or the substituted styrene;

- 20% to 50% by weight of the second copolymerization mixture of the acrylate and/or methacrylate;

- 5% to 20% by weight of the second copolymerization mixture of one or more ethylenically unsaturated monomers (e.g., acrylate, methacrylate, styrene); and

- 20% to 50% by weight of the second copolymerization mixture of a not-yet- polymerizable form of the polymerizable polymer.

Thus, by increasing the fraction of the not-yet-polymerizable form of the

polymerizable polymer (e.g., naturally occurring starch), the swelling capabilities of the polymer generated by the copolymerization are increased. By decreasing the fraction of the not-yet-poiymerizable form of the polymerizable polymer, the swelling capabilities of the polymer generated by the copoiymerization are decreased.

According to further embodiments, the generation of the copolymer of the first latex comprises performing a copoiymerization of a first copoiymerization mixture and the generation of the copolymer of the second latex comprises performing a

copoiymerization of a second copoiymerization mixture. The first and the second copoiymerization mixture respectively comprise:

- 20% to 40% by weight the styrene or the substituted styrene;

- 20% to 50% by weight the acrylate and/or methacrylate;

- 5% to 20% by weight the one or more ethylenically unsaturated monomers,

- 1 % to 50% by weight the not-yet polymerizable form of the polymerizable

polymer; thereby, the second copoiymerization mixture comprises at least 10% by weight more of the not-yet polymerizable form of the polymerizable polymer than the first copoiymerization mixture. Preferably, the second copoiymerization mixture comprises at least 20% by weight more of the not-yet polymerizable form of the polymerizable polymer than the first copoiymerization mixture. For example, the first copoiymerization mixture can comprise 35% of the not-yet polymerizable starch and the second copoiymerization mixture can comprise 50 % f the not-yet polymerizable starch. The higher the difference in weight structure of the not-yet polymerizable polymer, the stronger the mechanical shear forces resulting from water contact and the faster the degradation of any material generated from an inhomogeneous mixture of the two different latex forms.

According to embodiments, the generation of the inhomogeneous liquid mixture of the first and second latex comprises stirring the first liquid latex with the second liquid latex under stirring conditions that are known to yield a liquid latex mixture having a desired degree of inhomogeneity. The desired degree of inhomogeneity is a degree of inhomogeneity that causes a solidified film of the first and second latex to disintegrate into fragments of a desired size in response to contact with water. For example, it may be desired to apply a secondary backing that disintegrates into pieces that are about a size of 0.2-2 cm after one hour of water contact. In order to determine the desired degree of inhomogeneity and the corresponding stirring conditions (duration, stirring speed, etc.), different mixtures (test mixtures) of the first and second latex may be created. Each of the test mixtures is stirred under different conditions (stirring speed, stirring duration, optionally also stirrer type or

temperature, etc.). The test mixtures are applied on an even layer and are allowed to dry to form a solid film. The film is then submerged in water. After a predefined time (e.g., one hour), the films will have disintegrated, and the sizes of the

fragments are determined. The stirring conditions that yield a desired degree of inhomogeneity and a corresponding desired fragment size are then used for generating the liquid mixture of the first and second latex.

According to embodiments, the method further comprises generating an

inhomogeneous test latex mixture, the test mixture comprising the first and second latex that will be used for producing the backing of the hybrid turf support or the artificial turf. The test mixture is applied on an even surface and allowed to solidify and dry to form a test latex film. When the test latex film has dried, it is put in contact with water for a predefined time; e.g., one hour. The time of exposure is the desired backing disintegration time upon exposing the backing to water; e.g., to rainfall or irrigation. After the predefined time has elapsed, check whether the film has disintegrated. If the film has disintegrated, the first and second latex types used for generating the test latex mixture are used for manufacturing the backing of the artificial turf or the backing of the support. If the film has not disintegrated (to a sufficient degree), the composition of the first and/or second latex is changed in a way that the water-swelling capabilities of the first and second latex differ more strongly. Then, a new test !atex mixture is generated comprising the first and/or second latex with modified composition. And the test is repeated to check whether the swelling capabilities of the different latex form in the new test latex mixture cause the backing to disintegrate in the water exposure test to a sufficient degree.

The generation of the polymers can be performed, for example, as described in patent application US20130276245A1 , which is incorporated in its entirety hereby by reference. US20130276245A1 describes a composition for surface coloration of paper. It has nothing to do with artificial turf production. Embodiments of the invention are based on the surprising observation that the copo!ymerization described for generating the composition for surface coloration allows us to exactly define the swelling capability of latex by choosing appropriate amounts of comonomers, whereby at least one of said comonomers is in fact a water-swel!able polymer.

According to embodiments, the first copolymerization mixture and the second copolymerization mixture are free of pigments. According to embodiments, the copolymerization is a radical emulsion

polymerization of the copolymerization mixture.

According to embodiments, the inhomogeneous liquid mixture comprises about 50% by weight the first (less water-swellable) latex and comprises about 50% by weight the second (water-swellable) latex. However, other ratios of first to second latex are also possible; e.g., 1 .4: 1 or 1 :1.4.

According to embodiments, the inhomogeneous liquid mixture further comprises at least 10% by its weight a filler material, e.g., chalk, fine sand, CFA (cold fly ash), caoline, or ATH (aluminia trihydrate). In some examples, more than 50 % by weight of the inhomogeneous liquid mixture consists of the filler material. Adding a filler material may have the advantage that the disintegration of the backing is

accelerated, material costs are reduced and the weight of the artificial turf mat is increased. An increased weight may ease the installation of the artificial turf at the use site.

According to embodiments, the method further comprises:

- installing the support for hybrid turf manufactured according to an embodiment of the invention in a sod farm or at a use site; and

- exposing the installed support to rain or irrigation to cause the backing to

disintegrate; the disintegration is a result of a bringing the backing comprising the first and second latexes having different water-swelling capabilities in contact with water.

According to embodiments, the method further comprises:

- installing the artificial turf manufactured according to an embodiment of the

invention at a use site; and

- exposing the installed artificial turf to rain or irrigation to cause the backing to disintegrate; the disintegration is a result of bringing the backing comprising the first and second latexes having different water-swelling capabilities in contact with water.

According to embodiments, the incorporation of the artificia! turf fiber in the carrier structure comprises tufting or knitting the artificia! turf fibers in the carrier structure of the support. For example, the carrier structure can be a synthetic mesh or a combination of a synthetic mesh and a biodegradable mesh; e.g., a jute or sisal mesh.

According to embodiments, the artificial turf comprises a carrier structure that forms the layer. The incorporation of the artificial turf fiber in the layer comprises tufting or knitting the artificial turf fibers in the carrier structure. For example, the carrier that forms the layer can be a synthetic mesh or a porous material that allows for tufting or knitting the artificial turf fibers into the carrier structure. Using a carrier structure may have the advantage of increased stability of the artificial turf and of increased weight that may ease the stable fixation of the artificial turf at the use site. According to alternative embodiments, the generation of the layer of the artificial turf fibers comprises interweaving the artificial turf fibers with each other or with support fibers, thereby generating the layer in the form of a woven fabric. The artificial turf is free of a carrier structure for incorporating the artificial turf fibers. The artificial turf preferably is also free of any additional layers for increasing the stability of the artificial turf. Thus, there may not exist a carrier structure into which the fibers are incorporated. Rather, the fibers are interwoven with each other or with other fibers (support fibers). This weaving process generates the layer in which the artificial turf fibers are incorporated.

The "first" parts of the fibers (i.e., the long fiber parts that form the artificial grass blades) are arranged such that they extend to the upper side of the artificial turf layer, while the "second" parts of the fibers (e.g., U-turns or knots of a tufting or knitting process or the parts of an interwoven artificial turf fiber that faces the lower side) extend (at least to a dimension that corresponds to the diameter of a single fiber) to the lower side of the layer. According to embodiments, the liquid backing is applied to the lower side of the support or the lower side of the fiber-comprising layer of the artificial turf such that 5 more than 10% but less than 70% and preferably less than 50% of the lower side of the support or layer is sealed by the backing. This may further prevent an accumulation of water. The degree of sealing may depend in the grain size of the infill, e.g. sand, as the infill are supposed to reside in the fibres above the backing and must not fall through the backing.

According to embodiments, the artificial grass fibers consist of a single

monofilament or a bundle of two or more monofilaments. A monofilament is an extrusion product or a stripe generated by slicing an extruded polymer film.

According to embodiments, the support is used for generating hybrid turf for installation at sports fields and golf courses. This may be particularly advantageous for golf courses, which are irrigated frequently, so the risk that slack water and an anaerobe environment damages the roots of the grass plants is particularly high. Said risk can be reduced by a backing that disintegrates upon contact with water, thereby improving drainage and aeration. In a further aspect, the invention relates to a support for hybrid turf. The support comprises:

- a carrier having an upper side and a lower side;

- artificial turf fibers incorporated into the carrier, wherein the first portions of the incorporated artificial turf fibers protrude from the upper side and the second portions of the artificial turf fibers protrude from the lower side, with the first portions forming artificial grass blades; and

- a backing on the lower side of the carrier, the backing being a solidified,

inhomogeneous latex mixture of a first latex and a second latex; the first latex in the dry state being less water-swellable than the second latex in the dry state; and the backing contacting at least the second portions and mechanically fixing the artificial turf fibers in the carrier.

In a further aspect, the invention relates to artificial turf comprising:

- a layer of artificial turf fibers, the layer having an upper side and a lower side, wherein the first portions of the artificial turf fibers protrude from the upper side and the second portions of the artificial turf fibers protrude from the lower side, with the first portions forming artificial grass blades; and - a backing on the lower side of the layer, the backing being a solidified,

inhomogeneous latex mixture of a first latex and a second latex; the first iatex in the dry state being less water-swellable than the second Iatex in the dry state; and the backing contacting at !east the second portions and mechanically fixing the artificial turf fibers in the layer.

According to embodiments of the artificial turf or the support, the different swelling properties of the first and second Iatex result in water-induced disintegration of the backing.

The term "iatex" as used herein refers to a stable dispersion (emulsion) of polymer micro particles in an aqueous medium. In some embodiments, the first and/or the second Iatex is a Iatex form that is found in nature, but in other embodiments synthetic latexes are used as the first and/or second Iatex. Synthetic Iatex can be made by polymerizing a monomer such as styrene that has been emulsified with surfactants. Alternatively, synthetic Iatex can be made by polymerizing two or more different forms of monomers (referred herein as "comonomers"). This form of Iatex is also referred to as "hybrid Iatex." For example, a particular form of hybrid Iatex can be generated in a copolymerization reaction of acrylate, styrene, and a water- sweilable polymer.

According to embodiments, a„hybrid turf support" or„support for hybrid turf" as used herein comprises a materia! providing at least temporarily some mechanical support for hybrid turf. For example, a hybrid turf support can have the form of a support structure, layer or mat for hybrid turf.

A "polymerizable polymer" is a polymer that comprises one or more groups that allow the polymer to react with other molecules, referred to herein as

"comonomers," in a copolymerization reaction to form a copolymer. Many naturally occurring polymers like stark are chemically quite inert and cannot be used directly in a copolymerization reaction. By using one or more molecules that are abie to act as comonomers in a polymerization reaction (e.g., an acrylate, a methacry!ate, a styrene, or a substituted styrene) with the chemically inert polymer (e.g., stark), the polymer is made more reactive and is referred to herein as a "polymerizable polymer." The term "tufting" refers to a type of textile processing in which a thread is inserted on a primary base. It is an ancient technique for making warm garments, especially mittens. Short, U-shaped loops of extra yarn are introduced through the fabric from the outside so that their ends point inward (i.e., toward the hand inside the mitten). Usually, the tuft yarns form a regular array of "dots" on the outside. On the inside, the tuft yarns may be tied for security, although they don't need to be. Tufting may provide for a strong fixing of the artificial turf fiber in a carrier structure. Tufting may also be beneficial as it consumes less fiber material than weaving for achieving a desired density of artificial turf fibers emanating from a carrier. This is because it is not necessary to weave a fiber portion of significant length into an existing carrier structure or to generate a carrier textile structure by the weaving process. Rather, only a comparatively small portion, typically below 20% or even below 15% of a fiber, is contained within or at the lower side of the layer or carrier structure wherein the fibers are incorporated. According to embodiments, the "lower side" (LS) of a carrier structure (or fiber- comprising layer of artificial turf) is the side of the support (artificial turf) that points to the ground when installed on a sod farm or use site, while the "upper side" (US) refers to the opposite direction.

The term "hybrid grass" or "reinforced natural grass" as used herein refers to a product created by combining natural grass with artificial turf fibers. It is used, for example, for stadium fields and training fields used for soccer, rugby, football, golf, and baseball. Reinforced natural grass can also be used for events and concerts. The incorporated synthetic fibers make the grass stronger and more resistant to damage. The term "synthetic" (e.g., in "synthetic fiber" or "synthetic polymer") as used herein refers to an entity that is mainly or entirely made from synthetic materials such as petrochemicals, unlike those manmade fibers derived from such natural substances as cellulose or protein. In particular, a synthetic fiber can be a synthetic polymer fiber; e.g., a synthetic po!yo!efin fiber. A synthetic fiber can be made, for example, from polypropylene, polyethylene, nylon, PVC, PTFE (polytetrafluoroethylene) or other materials. The term "sod farm" or "sod grass farm" as used herein refers to an agricultural company and farm that grows and sells turf.

The term "use site" as used herein refers to a location where natural, hybrid, or artificial turf is to be installed and used. For example, turf is used for sports stadiums, lawns, and golf courses.

A "monofilament" as used herein is a fiber generated by extruding a polymer mass through an opening of an extruder. It is not generated by slicing a polymer film into stripes. Extruded monofilaments tend to be more robust against splicing and shear forces than fibers generated from a slit film.

Brief description of the drawings

In the following, embodiments of the invention are explained in greater detail, by way of example only, making reference to the following drawings:

Fig. 1 a is a photograph of two vessels filled with water and a film made of an in- homogeneous mixture of two latex forms that disintegrates on contact with water.

Fig. 1 b shows a photograph of a film made of an inhomogeneous mixture of two latex forms immediately after contact with water and a photograph of the same film one hour later. Fig. 2a is a flowchart of a method for producing a support mat for hybrid turf.

Fig. 2b is a flowchart of a method for producing artificial turf.

Fig. 3 depicts a piece of woven artificial turf that is free of a carrier material.

Fig. 4 depicts a support mat for hybrid turf before and after natural grass plants have started growing on the mat. Fig. 5 is an illustration of a latex film consisting of an inhomogeneous mixture of a first and a second latex. depicts two different copolymerization mixtures used for generating the polymer of the first and second latexes. Fig. 1a is a photograph of two vessels filled with water and a film made of an in homogeneous mixture of two latex forms. As the two different latex forms have different water-swelling capabilities, the film disintegrates in response to contact with water. The vessel 150 shows a single coherent piece of a test latex film that was created by hardening an inhomogeneous mixture of two different latex forms having different water-swelling capabilities. The test latex film in the vessel 150 is stili intact because the photograph was taken immediately after the film was immersed in water. The vessel 52 shows fractions of another piece of the test film that was immersed in the water of the vessel 152 about one hour earlier. The fractions of the latex film in the vessel 152 were generated as a result of a disintegration process along the contact areas of the first and second latexes in the inhomogeneously mixed latex film.

Fig. 1 b shows a photograph of a piece of another test film. The other test film is also made of an inhomogeneous mixture of two latex forms that have different water- swelling capabilities. For example, the first latex type in dry form may swell by 10% of its size if put in contact with water for one hour, while the second latex type may swell by more than 100% of its size if put in contacted with water for one hour.

Figure 1b shows a photograph of a piece 154 of the other test film that was made immediately after the piece of the other latex test film was submerged in a water bath. In addition, figure 1 b depicts a photograph of a further piece 156 of the other test film that was made about one hour after the piece of the other latex test film was submerged in a water bath.

The size of the fragments depends on the degree of inhomogeneity of the latex mixture used for generating the backing and/or the test fiim. The longer the two latex forms are mixed and stirred together, the more homogeneous the latex mixture, and the smaller the fragments generated by contacting the hardened latex backing/film with water.

Fig. 2a is a flowchart of a method for producing a support 200 for hybrid turf. Fig. 2c is a flowchart of a method for producing artificial turf 140. In the following, figures 2a and 2b will be described in greater detail by making reference also to elements of figures 3-7. The method for producing a support 200 for hybrid turf comprises step 102 of incorporating artificial turf fibers 310 into a carrier 206. The carrier can be, for example, a synthetic mesh and/or a jute mesh. The carrier has an upper side (US) and a lower side (LS). The first portions of the incorporated artificial turf fibers protrude from the upper side, and the second portions of the artificial turf fibers protrude from the lower side. The first portions form artificial grass blades. In step 104, an inhomogeneous liquid mixture of a first latex 602, 706 and a second latex 604, 708 is generated. The first latex in the dry state is less water-swellable than the second latex in the dry state. In step 106, after having incorporated the artificial turf fibers, the inhomogeneous liquid mixture is applied on the lower side of the carrier such that the inhomogeneous liquid latex mixture wets at least the second portions. Then, in step 108, the inhomogeneous liquid latex mixture is allowed to solidify to form a solid backing 220 of the support. The backing mechanically fixes the artificial turf fibers in the carrier. The carrier, the backing, and the incorporated artificial turf fibers together form the support.

Fig. 2b is a flowchart of a method for producing artificial turf 40. The method comprises generating, in step 112, a layer 132 of artificial turf fibers 130. The layer has an upper side US and a lower side LS. The first portions of the artificial turf fibers protrude from the upper side, and the second portions of the artificial turf fibers protrude from the lower side. The first portions form artificial grass blades 130. In step 114, an inhomogeneous liquid mixture of a first latex 602, 706, and a second latex 604, 708, is generated. The first latex in the dry state is less water-swellable than the second latex in the dry state. In step 1 16, the inhomogeneous liquid mixture is applied on the lower side of the layer such that the inhomogeneous liquid latex mixture wets at least the second portions. In step 1 18, the inhomogeneous liquid latex mixture is allowed to form a solid backing of the artificial turf. The backing mechanically fixes the artificial turf fibers in the layer. The backing and the layer of artificial turf fibers form the artificial turf.

Fig. 3 depicts a piece of woven artificial turf 140 according to one embodiment of the invention. The artificial turf 140 is free of a carrier material. Rather, the artificial turf fibers 130 are interwoven with each other or with some support fibers to generate a woven textile layer 32. The layer preferably comprises large openings that ensure that rain can penetrate the layer 132 and infiltrate the soil. The carrier materiaf-free artificial turf 140 is particularly light and flexible, but has the disadvantage that it has reduced stability and may become easily detached from the ground. By applying a backing to the lower side LS of the artificial turf 140 by a method as described (e.g., for figure 1 b), the stability of the artificial turf 140 can be increased. This may be advantageous for transporting the artificial turf and for installing it at the use site. Nevertheless, as the backing will disintegrate after the occurrence of one or more rain showers, it is ensured that water will always be able to penetrate the installed artificial turf and to infiltrate the ground.

Fig. 4 depicts a support 200 for hybrid turf that was installed at a sod farm. Figure 4a shows the mat before and figure 4b shows the mat after natural grass plants have started growing on the mat.

The support 200 consists of a plurality of artificial turf fibers 310 that have been incorporated (e.g., tufted) into a carrier structure. The fibers are additionally fixed in the carrier structure by a backing layer 220 consisting of an inhomogeneous !atex mixture as described herein for embodiments of the invention.

The carrier structure may comprise a synthetic mesh 206; e.g., a polyethylene (PE) mesh.

The support 200 is transferred to a sod farm, where it is placed on top of a ground layer 302 comprising sand or earth or a mixture thereof. The ground layer 302 may also consist of synthetic filler materials and is of sufficient height to allow grass roots to mechanically penetrate the layer and extract nutrients and water; e.g., at least 2- 3 cm.

After the support 200 is installed on the ground layer 302 of the sod farm, a fill layer 306 is added on top of the support. The fill layer comprises fill material. For example, the fill layer may comprise sand, earth, synthetic filler materials, or a mixture thereof. The fill layer may optionally also comprise or may later be supplemented with fertilizers, minerals, fungicides, etc. According to embodiments, the fill layer has a height of 10-50 mm, preferably in the range of 20^10 mm. Using a thin fill layer may be advantageous, as the roots will penetrate and mechanically fix at least parts of the fill layer on top of the multilayer structure. Thus, the fill layer will have to be moved at least partially from the sod farm to the use site. This increases the weight of the hybrid turf and thus increases transport costs. As the backing firmly fixes the fibers in the multilayer carrier structure, a thin fill layer may be sufficient to protect the fibers from being pulled out. Thus, transport costs may be reduced. The support depicted in Fig. 4a is root-, air-, and water-permeable. Because the solidified backing 220 is disrupted upon contact with water, the roots have sufficient space to grow without clogging the openings of the remaining mesh 206 and thus without making the support water-impermeable. The backing 220 stabilizes the support during transport from the artificial turf factory to the sod farm, and in the early phase of growing the natural grass. The mesh 206 that is still intact when the natural grass has reached the desired length stabilizes the hybrid turf when it is transported from the sod farm to the use site, such as a golf course. As the roots remain largely intact, the overall time needed for achieving a playable and durable hybrid turf is reduced. According to embodiments, both the artificial grass blades as well as the natural grass blades extend more than 20 mm or even more than 40 mm above the upper surface of the fill layer. As the support carries the filler material (e.g., sand-based growth media), only a comparatively small fraction of the roots will reach down to the base layer 302, so the root system can be transplanted in a comparatively intact form. The sod farm provides lighting and irrigation systems 305 which allow for an optimum growth rate of the natural grass plants. Warm temperatures and constant humidity accelerate not only the growth of the plants but also the disintegration of the backing 220 into small fragments and may optionally also accelerate

biodegradation of the water-swellable polymer component; e.g., starch. Thus, the roots 308 of the grass plants have sufficient space to grow without clogging the support 200.

Fig. 4b depicts the installation of the grown hybrid turf at the use site: the soil 314 at the use site may be, for example, clay or sand or any other form of soil that supports the growth of grass. A small fraction of the base layer 302 may be bound by the roots 308 of the plants and transported to the use site. The natural grass fibers 312 are depicted in black, the artificial turf fibers 310 in grey. The natural grass blades intermix with the artificial turf fibers and form a piece of hybrid turf 300. When the natural grass has reached its desired length, the backing 220 has already disintegrated into small fragments and may even have been largely or completely degraded without a negative impact on the stability of the hybrid turf. The fill layer supports the roots and crowns of the natural grass plants, and the grass blades of the natural grass plants as well as a large portion of the artificial turf fibers 310 extend above the fill layer to create a hybrid grass surface that faithfully reproduces a natural grass surface. The support "carries" the natural grass plants and the fill layer.

Fig. 5 is an illustration of a latex film 600; e.g., a test latex film used for testing whether the fiim disintegrates fast enough upon contact with water. The film consists of an inhomogeneous mixture of a first latex 602 and a second latex 604 having different water-swelling properties. The first latex may not swell at all or may swell only weakly, while the second latex may strongly increase its volume; e.g., by more than 50% or even by more than 100% of its original volume. The second latex in film 600 was supplemented with some pigments for test and illustration purposes only. The !atex mixture that is actually used for generating the backing preferably is free of any pigments. As the swelling behavior of the first and second latexes is different, mechanical shear forces occur at locations where the first and second latexes are in contact with each other if the film is submerged in water and will create microscopic and/or macroscopic cracks that result in the disintegration of the test film or the backing (as illustrated in Fig. 1).

Fig. 6 depicts two different copolymerization mixtures used for generating the polymers 706, 708 of the first and second latexes. The first mixture 702 is used for generating the polymer 706 of the first latex, and the second mixture 704 is used for generating the polymer 708 of the second latex. The polymers 706, 708 are copolymers generated in a copolymerization reaction. The type and/or relative amount of the comonomers 710, 712, 716 in the mixtures may be different and may be chosen such that the resulting polymers 706, 708 have different water-swelling properties. The polymer 706 of the first latex is preferably a copolymer of: i. styrene or a substituted styrene 710; ii. an acrylate and/or methacrylate and/or butadiene 712; and iii, a polymerizable form 716 of a swellable polymer; e.g., an ethylenically

unsaturated starch.

In the following, the generation of the first polymer 706 having a comparatively weak swelling capability according to one possible embodiment is described.

The polymer 706 of the first latex can be obtained, e.g., by copolymerization of a degraded, oxidized anionic starch 716 which represents a polymerizable form of the comparatively inert starch 714.

For example, the polymer 706 of the first latex can be obtained by emulsion polymerization of a first mixture 702 of monomers. The polymerization can be a radical polymerization using hydroperoxide or AIBN (azobisisobutyronitrile) as radical initiators.

According to embodiments, the first mixture 702 of monomers consists of: i. from 20% to 40% by weight of the first copolymerization mixture of styrene or a substituted styrene 712; ii. from 20% to 50% by weight of the first copolymerization mixture of an

acrylate and/or a methacrylate and/or butadiene 712; iii. from 5% to 20% by weight of the first copolymerization mixture of one or more ethylenically unsaturated monomers (e.g., acrylate, methacrylate, styrene); said monomers are given in addition to components i and ii and are added for generating polymerizable (grafted) forms of the not-yet- polymerizabie polymer (starch); and iv. 1 % to 5% by weight of the first copolymerization mixture of a not-yet- polymerizable form of the polymerizable polymer. For example, the first mixture can comprise 40% styrene, 50% acrylate, 4% methacrylate, and 6% starch.

According to embodiments, the second mixture 704 of monomers consists of: i. from 20% to 40% by weight of the second copolymerization mixture of styrene or a substituted styrene 712; ii. from 20% to 50% by weight of the second copolymerization mixture of

acrylate and/or methacrylate and/or butadiene 712; iii. from 5% to 20% by weight of the second copolymerization mixture of one or more ethylenically unsaturated monomers (e.g., acrylate, methacrylate, styrene); said monomers are given in addition to components i and ii and are added for generating polymerizable (grafted) forms of the not-yet- polymerizable polymer (starch); and iv. 20% to 50% by weight of the second copolymerization mixture of a not-yet- polymerizab!e form of the polymerizable polymer.

For example, the second mixture can comprise 30% styrene, 30% acrylate, 10% methacrylate, and 30% starch.

Substituted styrenes may include, for example, a-methyl styrene, or styrenes substituted in the phenyl ring by alkyi groups, such as methyl, halogens, such as chlorine, or alkoxy groups, such as methoxy. However, styrene itself is the most preferred component.

Acrylates or methacrylates are preferably lower alkyi esters such as methyl; ethyl; n- or isopropyl; and n-, iso-, sec-, or tert-butyl esters or their mixtures; with n-butyl acrylate being the most preferred component.

The ethylenically unsaturated comonomer may be selected from a wide variety of compounds containing one single unsaturated double bond; i.e., excluding dienes of starch/latex copolymers such as 1 ,3-butadiene or isoprene. Examples of suitable ethylenically unsaturated monomers are hydroxylated alkyi methacrylates, alkyi vinyl ketones, substituted acryiamides, methacrylic acid, N-methylo! acrylamide, 2- hydroxyethyl acrylate, crotonic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, vinyl halides, vinylidene halides, vinyl esters, vinyl ethers, vinyl carbazole, N-vinyl pyrrolidone, vinyl pyridine, ethylene, propylene, isobutylene, vinyl triethoxy silane, and triphenyi vinyl silane. For example, ethylenicaily unsaturated comonomers can be dimethyl amino ethyl acrylate, dimethyl amino propyl acrylamide, vinyl acetate, acrylic acid, acrylamide, maleic anhydride, and monovinyl silicon compounds including vinyl trimethyl silane, ethyl vinyl ether, butyl vinyl ether, 2-ethylhexyl acrylate vinylidine chloride, butyl vinyl ether, and, especially, acrylonitrile.

According to embodiments, the not-yet-polymerizable polymer can be an oxidatively degraded anionic starch.

According to embodiments, the generated copolymers may advantageously be utilized in the form of aqueous dispersions ("latex"). These polymer dispersions generally contain between 20% and 50%, preferably between 25% and 35%, dry weight of solids. Aqueous dispersions of similar copolymers have been described in WO 00/46264, which document also discloses a process for their preparation.

Starch or starch derivatives suitable for incorporating into the final copolymer 706, 708 may include practically all thinned starches of plant origin including starches from corn, wheat, potatoes, tapioca, rice, sago, and sorghum. Waxy and high- amylose starches may also be suitable. The starches can be thinned by acid hydrolysis, oxidative hydrolysis, or enzymatic degradation. Further derivatized starches also suitable include those such as starch ethers, starch esters, cross- linked starches, oxidized starches, and chlorinated starches— for example, carboxymethyj cellulose and hydroxyethyl methyl cellulose. Typical examples are the commercially available amylopectin and dextrin. A commercially available example of oxidized starch is Perfectamyl^® 4692.

According to embodiments, the first and/or second latex may contain further auxiliaries selected from fixing agents, dispersants, additional binder and binder resins, antifoams, and biocides.

Once the first and second latexes have been created, they can be combined in a tank and mixed by a stirrer under defined conditions for a defined time to ensure that the two latex forms are mixed but not homogeneously mixed to ensure that the inhomogenities of the latex composition of the backing will result in the desired size of the fragments when the backing contacts water. The inhomogeneous latex mixture can be applied to the lower side of the carrier or fiber layer by spraying, curtain coating, or conventional coating processes used for coating artificial turf and hybrid turf support. Optimal conditions for stirring speed and stirring duration for generating a desired degree of inhomogeneity can be easily determined

experimentally by generating a latex film from a mixture of the first and second latexes that was stirred under defined conditions for a defined time, and then submerging the dried latex film in water for one hour. After one hour, the number and sizes of the fractions of the film generated by the swe!ling-induced expansion are examined. If the fragments are too large, the stirring speed or duration is increased. If the fragments are too small and optionally also incomplete, the stirring speed or duration is reduced. If no fragments appear at all, the stirring is either way too strong so that a homogeneous latex mixture was created or the difference in the swelling behavior of the first and second latexes is not high enough to disrupt the film. In this case, the composition of at least the first or the second latex is modified.

The two different forms of a starch-latex copolymer described above are only one example for using an inhomogeneous mix of two different latex forms having different water-swelling capabilities. For example, there exist various ready-to-use latex forms that are designed and used as binders in the pigmented paper industry. By experimentally determining the water-swelling capabilities of the available latex forms and by inhomogeneously mixing latex forms having different swelling properties, a backing layer for artificial turf and hybrid turf support can be generated that disintegrates upon contact with water. For example, the commercially available latex BEL2102 can be used as the first latex that swells only very weakly, and BEL2100 can be used as the second latex that swells strongly if brought into contact with water. For example, a 1 :1 mixture of the two latex forms may be used.

List of reference numerals

102-108 steps

112-1 18 steps

130 artificial turf fibers

132 layer

140 artificial turf without a backing

150 vessel with submersed latex film

152 vessel with submersed, degraded latex film

154 water bath with submersed latex film

156 water bath with submersed, degraded latex film

200 support for hybrid turf

206 carrier structure, e.g. mesh

220 solidified backing

300 hybrid turf

302 base layer

305 illumination and/or irradiation systems

306 fill layer

308 grass roots

310 artificial turf fibers

312 natural grass blades

600 latex film

602 areas basically consisting of first latex

602 areas basically consisting of second latex

702 first co-polymerization mixture

704 second co-po!ymerization mixture

706 copolymer comprised in the first latex

708 copolymer comprised in the second latex

710 styrol or styrol derivative used as co-monomer

712 acrylate or methacrylate used as co-monomer

714 swellable, not polymerizable polymer, e.g. starch

716 swellable, polymerizable polymer, e.g. starch grafted on acry!ate or styrol, used as co-monomer

Claims

C l a i m s

1 . A hybrid turf support for use with natural grass to form a stable hybrid turf

system, the hybrid turf support comprising: (a) a carrier having an upper side and a lower side;

(b) a plurality of artificial turf fibers engaging with the carrier, first portions of the artificial turf fibers protrude from the upper side of the carrier, and second portions of the artificial turf fibers protrude from the lower side of the carrier; the first portions of the artificial turf fibers form artificial grass blades; and (c) a backing on the lower side of the carrier, the backing comprising a solidified inhomogeneous liquid mixture of a first latex and a second latex; wherein the first latex in the dry state is less water-swellable than the second latex in the dry state; wherein, in use, the different swelling properties of the first and second latex result in water-induced disintegration of the backing.

2. A method of producing a support (200) for hybrid turf, the method comprising:

- Incorporating (102) artificial turf fibers (310) into a carrier (206, 216), the carrier having an upper side (US) and a Sower side (LS), wherein first portions of the incorporated artificial turf fibers protrude from the upper side and second portions of the artificial turf fibers protruding from the lower side, the first portions forming artificial grass blades;

- generating (104) an inhomogeneous liquid mixture of a first latex (602, 706) and a second latex (604, 708), the first latex in the dry state being less water-swellable than the second latex in the dry state;

- after having incorporated the artificial turf fibers, applying (106) the

inhomogeneous liquid mixture on the lower side of the carrier such that the inhomogeneous liquid latex mixture wets at least the second portions; and solidifying (108) the inhomogeneous liquid latex mixture to form a solid backing (220) of the support, the backing mechanically fixing the artificial turf fibers in the carrier, the carrier with the backing and the incorporated artificial turf fibers forming the support. A method of producing artificial turf (140), the method comprising:

- generating (1 12) a layer (132) of artificial turf fibers (130), the layer

having an upper side (US) and a lower side (LS), wherein first portions of the artificial turf fibers protrude from the upper side and second portions of the artificial turf fibers protruding from the lower side, the first portions forming artificial grass blades (130);

- generating (114) an inhomogeneous liquid mixture of a first latex (602, 706) and a second latex (604, 708), the first latex in the dry state being less water-swellable than the second latex in the dry state;

- applying (1 16) the inhomogeneous liquid mixture on the lower side of the layer such that the inhomogeneous liquid iatex mixture wets at least the second portions; and

- solidifying (118) the inhomogeneous liquid Iatex mixture to form a solid backing of the artificial turf, the backing mechanically fixing the artificial turf fibers in the layer, the backing and the layer of artificial turf fibers forming the artificial turf.

The hybrid turf support of claim 1 or the method of either one of claims 2 or 3, the first and/or the second Iatex respectively being an emulsion of a copolymer (706, 708) in an aqueous medium, the copolymer being a copolymerization product of a polymerizable polymer (716) and one or more monomers, the one or more monomers being selected from a group comprising:

- styrene or a substituted styrene (710);

- an acrylate and/or methacrylate (712).

The hybrid turf support or the method of claim 3, the polymerizable polymer (716) being water-swellable.

The hybrid turf support or the method of claim 3 or 4, the polymerizable polymer (716) being polymerizable starch or a polymerizable starch derivative.

7. The hybrid turf support or the method of any one of claims 3-5, further comprising generating the copolymer (706) of the first Iatex and/or the copolymer (708) of the second Iatex by copolymerization of a copolymerization mixture (702, 704) comprising:

- styrene or the substituted styrene (7 0);

- acrylate and/or methacry!ate (712);

- one or more ethylenicaiiy unsaturated monomers;

a not-yet poiymerizable form (714) of the poiymerizable polymer (716). 8. The hybrid turf support or the method of claim 6, the generation of the

copolymer (706) of the first iatex comprising performing a copolymerization of a first copolymerization mixture (702) comprising:

- 20% to 40% by weight of the first copolymerization mixture the styrene or the substituted styrene (710);

- 20% to 50% by weight of the first copolymerization mixture of the

acrylate and/or methacrylate (712);

- 5% to 20% by weight of the first copolymerization mixture the one or more ethylenicaiiy unsaturated monomers;

- 1 % to 15% by weight of the first copolymerization mixture the not-yet poiymerizable form (714) of the poiymerizable polymer (716).

9. The hybrid turf support or the method of any one of claims 3-6, the generation of the copolymer (708) of the second Iatex comprising performing a

copolymerization of a second copolymerization mixture (704) comprising:

- 20% to 40%) by weight of the second copolymerization mixture the styrene or the substituted styrene (710);

- 20% to 50% by weight of the second copolymerization mixture the acrylate and/or methacrylate (712);

- 5% to 20% by weight of the second copolymerization mixture the one or more ethylenicaiiy unsaturated monomers,

- 20% to 50 % by weight of the second copolymerization mixture of the not-yet poiymerizable form (714) of the poiymerizable polymer (716).

10. The method of claim 6,

wherein the generation of the copolymer (706) of the first latex comprises performing a copolymerization of a first copolymerization mixture (702), wherein the generation of the copolymer (708) of the second latex comprises performing a copolymerization of a second copolymerization mixture (704), wherein the first and the second copolymerization mixture respectively comprise:

- 20% to 40% by weight the styrene or the substituted styrene (710);

- 20% to 50% by weight the acrylate and/or methacrylate (712);

- 5% to 20% by weight the one or more ethylenically unsaturated

monomers,

- 1 % to 50% by weight the not-yet polymerizable form (714) of the

polymerizable polymer (716), wherein the second copo!ymerization mixture comprises at least 10% by weight more of the not-yet polymerizable form (714) of the polymerizable polymer (716) than the first copolymerization mixture.

1. The method of any one of the previous claims 3-10, the co-polymerization being a radical emulsion polymerization of the copolymerization mixture.

2. The method of any one of the previous claims, the inhomogeneous liquid

mixture comprising at least 10% by its weight a filler material. 3. The method of any one of the previous claims, further comprising:

-installing the support for hybrid turf of claim 1 in a sod farm or at a use site; and

-exposing the installed support to rain or irrigation for causing the backing to disintegrate as a result of contacting the backing comprising the first and second latexes having different water-swelling capabilities with water.

14. The method of any one of the previous claims, further comprising:

-installing the artificial turf of claim 2 at a use site; and -exposing the installed artificial turf to rain or irrigation for causing the backing to disintegrate as a result of contacting the backing comprising the first and second latexes having different water-swelling capabilities with water.

The method of any one of the previous claims 1 , 3-12, the incorporation of the artificial turf fiber in the carrier structure comprising tufting or knitting the artificial turf fibers in the carrier structure of the support.

The method of any one of the previous claims 2-12, the artificial turf comprising a carrier structure that forms the layer, the incorporation of the artificial turf fiber in the layer comprising tufting or knitting the artificial turf fibers in the carrier structure. 7. The method of any one of the previous claims 2-12, the generation of the layer of the artificial turf fibers comprising interweaving the artificial turf with each other or with support fibers, thereby generating the layer in the form of a woven fabric (132), the artificial turf being free of a carrier structure for incorporating the artificial turf fibers, the artificial turf preferentially being also free of any additional layers for increasing the stability of the artificial turf.

18. The method of any one of the previous claims, the generation of the

inhomogeneous liquid mixture of the first and the second latex comprising: - stirring the first liquid latex with the second liquid latex under stirring conditions which are known to yield a liquid latex mixture having a desired degree of inhomogeneity, the desired degree of inhomogeneity being a degree of inhomogeneity that causes a solidified film of the first and second latex to disintegrate in response to water contact into fragments of a desired size.

19. A support (200) for hybrid turf comprising:

- a carrier (206, 216) having an upper side and a lower side, artificial turf fibers (310) incorporated into the carrier, wherein first portions of the incorporated artificial turf fibers protrude from the upper side and second portions of the artificial turf fibers protruding from the lower side, the first portions forming artificial grass blades;

a backing (220) on the lower side of the carrier, the backing being a solidified, inhomogeneous latex mixture of a first latex (602, 706) and a second latex (604, 708), the first latex in the dry state being less water- swellable than the second latex in the dry state, the backing contacting at least the second portions and mechanically fixing the artificial turf fibers in the carrier.

20. An artificial turf (140) comprising:

- a layer (132) of artificial turf fibers ( 30), the layer having an upper side (US) and a lower side (LS), wherein first portions of the artificial turf fibers protrude from the upper side and second portions of the artificial turf fibers protruding from the lower side, the first portions forming artificial grass blades (130);

- a backing on the lower side of the layer, the backing being a solidified, inhomogeneous latex mixture of a first latex (602, 706) and a second latex (604, 708), the first latex in the dry state being less water-swel!able than the second latex in the dry state, the backing contacting at least the second portions and mechanically fixing the artificial turf fibers in the layer.